1. Field of Invention
The present invention relates to micro electro-mechanical system (MEMS) device. More particularly, the present invention relates to MEMS microphone device with multi-sensitivity outputs.
2. Description of Related Art
MEMS device, such as MEMS microphone or the like device, is formed based on semiconductor fabrication process. As a result, the MEMS microphone or MEMS device can be in rather small size and can be implemented into various larger systems to sense the environmental signals, such as acoustic signal or acceleration signal.
The sensing mechanism of the MEMS device is based on a diaphragm, which can vibrate in responding to acoustic pressure or in responding to any factor, such as accelerating force, capable of causing deformation of the diaphragm. Due to the vibration or displacement of the diaphragm, the capacitance is changed, so as to be converted into electric signals used in subsequent application circuits.
Conventionally, one MEMS device has its own designed sensitivity. However, when the application system needs multiple sensitivities of the MEMS to meet the changing environmental condition, the conventional way may need to implement multiple MEMS devices with different sensitivities, so as to choose one of the multiple MEMS devices in use. This manner would at least cause a larger circuit cost.